A. Field of the Invention
This invention relates to a process for the coloring of an aluminum anodic oxide film.
B. Prior Art
Coloring processes of the above type are known in which aluminum or aluminum alloy members are colored by an alternating current electrolysis process. In this conventional process, any desired density of color can be obtained by properly selecting the time of coloring, but the color density for a given period of coloring time varies in each and every coloring operation. This is caused by various conditions of the coloring operation itself, for example, change of liquid temperature, shape of the members, change of the composition of the coloring electrolyte, change of the aluminum ion amount in the bath, agitating conditions of the bath etc. However, this can be minimized if the control is fully effected but, the variation of color density is still produced even if these conditions are satisfied absolutely.